The final phase of the flight of an airplane is normally broken down into an approach phase, a leveling-off phase ending with an impact on the ground and a taxiing phase of the airplane on the runway.
The quality of the approach phase is essential for the leveling-off procedure, the airplane needing to begin the latter with exact position, speed and attitude parameters.
The approach phase is therefore an important phase of the flight which largely determines the safety of the landing. In final approach, the pilots have conventional instrumental airplane information: the speeds, the height, the gradient of the airplane, alignment deviations relative to the axis of the runway (loc) and to the descent (glide) plane, the engine speed, and so on, which enable them to control the flight of the airplane.
From this instrumental information, the pilots, either in a manual or semi-automatic piloting mode, or in an automatic piloting mode monitoring function, try their best to reduce the deviations of the various flight parameters so that they achieve in a stable manner the values defined by the approach procedure. The instrumental information is also complemented by the visual perceptions of the environment which enable the pilots to assess their position relative to the approach plane.
A major proportion of the incidents or accidents involving airplanes occurs in final phases, such as, for example, tailstrikes, hard landings and longitudinal or lateral departures from the runway. One of the main causes of these incidents is associated with the fact that flight parameters of the airplane could not be correctly stabilized in the approach phase, and in particular when an airplane is too high or at too high a speed in its approach.
In most cases, if the pilots of the airplane, who have a high workload during this flight phase, had had a better awareness that the actual situation of their airplane would not have enabled them to achieve a landing in good conditions, the accidents could have been avoided by a go-around and a new approach in good conditions.
The US patent published under the number U.S. Pat. No. 7,068,187 proposes a method for assisting the pilots of an airplane in a go-around decision. Many parameters, such as, for example, the wind conditions on the runway, the speed of the airplane or the gradient of the airplane, are monitored during the approach phase, in order to detect the conditions of a non-stabilized approach, and a risk level is assessed. When the risk exceeds a certain threshold, an alarm is generated to warn the pilots of a need for a go-around.
However, the method described in this patent does not enable the pilots to know which parameters are forcing them to perform a go-around. This lack of knowledge of the reasons forcing the pilots to perform a go-around can induce among them a certain reluctance to execute a maneuver for which they do not know the motivation, particularly because of other possible criteria of choice which could be deemed more important by the pilots.
The French patent published under the number 2885439 proposes a method to assist in the piloting of an airplane in an approach phase with a view to a landing. More particularly, the method provides help in managing the energy in the approach phase, to assist the pilots in their decision whether or not to interrupt the approach phase with a go-around maneuver.
This method enables the pilots to check, before beginning the final approach phase, that they can reach the runway. However, in the final approach phase, the information concerning the closest point of contact with the ground is no longer relevant for the piloting. The pilots could, in practice, consider that they are able to reach the runway and therefore be urged unwittingly to continue an approach although said approach is not stabilized.